1. Field of the Invention
The invention generally relates to a reference frequency setting method, and more particularly, to a method of recording a reference frequency into a memory as a firmware, and a memory controller and a flash memory storage apparatus using the same.
2. Description of Related Art
Universal serial bus (USB) devices are very popular and mature products in the consumer market. In order to generate an accurate reference frequency in a USB device, an external circuit (i.e., a crystal oscillator circuit) is usually adopted. If the characteristic of an oscillator circuit in a chip is to be calibrated, conventionally, the manufacturer records the calibration setting in a hardware component (for example, an e-fuse or a trim pad) during the activation procedure. However, crystal oscillator circuit comes at high cost, and the surface area and hardware cost of the USB device will be increased by recording the frequency setting of the oscillator circuit in the chip. Besides, because the hardware component is fused after the USB device is activated, the frequency cannot be changed again. As a result, the competitiveness of the USB device is reduced.
Nothing herein should be construed as an admission of knowledge in the prior art of any portion of the present invention. Furthermore, citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention, or that any reference forms a part of the common general knowledge in the art.